Serial Auto Increment Field and Borland C Builder

Let me give a simple example of what I am trying to do:

CREATE SEQUENCE "usernumber" start 0 increment 1;

Create table users (
name varchar(255),
userid int4 DEFAULT nextval ( 'usernumber' ) NOT NULL);
);

>From Borland C++ Builder I create a form with a
link to the table "users", a navigator bar, and a DBedit object linked
to the field "userid".

When I post new record, an error is returned that "users.name" cannot be
null, which is true.

Now the question:

Is there a way to make Borland C++ Builder only
update the field "name" and let Postgresql take care of the
updating the serial field "userid"

Thanks,
Travis